Movement of the head about axes tilted from the vertical (off-vertical axis rotation) has a dramatic effect on the vestibulo-ocular reflex (VOR). It enhances compensatory responses and suppresses post-rotatory responses. Thus the effect of a rotating gravity vector on the VOR is similar to that of vision. The object of this research is to determine where in the labyrinth activity related to rotating gravity vectors arises, and how it is processed centrally. Specifically we wish to determine how it couples to the velocity storage mechanism in the VOR that is responsible for lengthening the time constant of the VOR and generating slow phases of nystagmus. This integrator also serves as a focus for visual-vestibular interactions. In the proposed experiments we will study the dynamics of eye movements during vertical and off vertical rotations and during rotation of the visual surround. These stimuli induce per and post rotatory nystagmus and optokinetic nystagmus (OKN) and optokinetic after nystagmus (OKAN). Extracellular unit activity will be recorded in the vestibular nerve the vestibular nuclei, the prepositus nucleus and the flocculus. Extracellular activity and eye movements will be analyzed in the time and frequency domains and compared to predictions made from central system models of the VOR. This research should help elucidate how and where gravity is sensed by the labyrinth, how visual and vestibular sensory information is combined centrally and how they contribute to production of compensatory eye movement against head movements in all planes.